Narrow Results

In this paper, alpha decay half-lives of spherical nuclei in the range $67\le Z\le 91$ are studied by considering the Coulomb and proximity potential model (CPPM) and calculating the alpha particle preformation factor. Comparisons are made to existing data in the literature. The half-lives are compared to the experimental values and also with the existing theoretical models, the analytical formula of Royer (R) and also within the modified analytical formula of Royer (MR) and New Akrawy–Poenaru Formula (AKRE) by Akrawy and Poenaru and the semi-empirical model based on fission theory (SemFIS) of Poenaru et al., the Universal Decay Law (UDL) of Qi et al., the Scaling Law of Brown (SLB), the Scaling Law of Horoi et al. (SLH). Compared with the experimental alpha half-lives, it can be found that the half-lives obtained using our formalism is in good agreement with the experimental data.

Alpha-decay half-lives of the even–even superheavy isotopes with proton numbers $120\le Z\le 126$ have been calculated within the cluster model. The alpha-daughter potential was constructed by employing the density-dependent double-folding model with a realistic nucleon–nucleon interaction whose exchange part has a finite range approximation. The half-lives were calculated using Wentzel–Kramers–Brillouin (WKB) approximation with the alpha preformation factor. The results have shown that the computed alpha-decay half-lives were in good agreement with their counterpart calculated by different semi-empirical approaches. The obtained results have also shown a negative linear relationship between the logarithm of the preformation factor and the fragmentation potential for the understudy isotopes. Also, the calculated results have shown that isotopes ${}^{304,296,318}120$, ${}^{296,300,306,318,326}122$, ${}^{312,318,324,332}124$ and ${}^{308,316,322}126$ had longer half-lives than their adjacent isotopes, which indicates that the corresponding neutron or proton numbers have a magical or semi-magical properties. Furthermore, we have studied the competition between alpha-decay and spontaneous fission to predict possible decay modes from the even–even isotopes $Z=120\text{–}126$. The results revealed that the isotopes ${}^{308\text{–}332}126$, ${}^{308\text{–}320}124$, ${}^{300\text{–}312}122$ and ${}^{290\text{–}308}120$ had alpha-decay as a predominant mode of decay and the nuclei ${}^{334\text{–}338}126$, ${}^{324\text{–}338}124$, ${}^{314\text{–}334}122$, and ${}^{310\text{–}328}120$ could not survive from the spontaneous fission. We hope that the theoretical prediction could be helpful for future investigation in this field.

The accurate calculations of the cluster formation model (CFM) have been extended to determine the alpha cluster preformation probability for the three even–even superheavy isotopes (Hs, Ds and Cn) with atomic number $Z=108,110$ and 112 and neutron numbers $144\le N\le 188$ in the mass region from 252 to 300. According to the hypothesized CFM, the calculations of the formation energy and surface energy, which depended on differences of binding energies are crucial for determining the realistic values of the preformation probability. Our results showed reasonable agreement with the results of previous work for the heavy nuclei. In addition, realistic values of the preformation probability certified that CFM can successfully be used to calculate the alpha cluster preformation probability for other wide range of superheavy nuclei.

We considered the systematics of Alpha-decay (AD) half-life (HL) of super-heavy nuclei (SHN) versus the decay energy and the total $\alpha$-kinetic energy. We have considered a potential model with Yukawa proximity potential and thereby calculated the HLs. Our results compared with experimental data and the empirical estimates. Also, we obtained $\alpha$-preformation factors from the ratio between theoretical and experimental results for a few super heavy nuclei. The results indicate the acceptability of the approach.

The influence of nuclear deformation on the α-decay half-lives of even-even nuclei from ground states to ground states is systematically investigated within the framework of a generalized liquid drop model (GLDM) by taking into account the deformation of the daughter nucleus. The preformation factors of α particle are extracted from the experimental α-decay half-lives of 158 even-even nuclei for 62 ≤ Z ≤ 118, and an analytic expression for calculating α clustering factor is proposed. The experimental half-lives are accurately reproduced and some predictions are reasonably made by employing the proposed preformation formula.